Revised conodont stratigraphy of the Cellon section (Silurian, Carnic Alps)

The Cellon section, located in the Carnic Alps, is a reference section for the Silurian of the world. The conodont association of the section is revised according to the most recent taxonomy and the biostratigraphy updated in the basis of the recently published zonation schemes. Seventy taxa (species and subspecies) belonging to 23 genera have been identified, allowing the discrimination of fifteen biozones from the upper Llandovery to the end of the Pridoli. However, some of the uppermost Llandovery and Wenlock biozones, corresponding to black shale intervals, have not been documented

Upper Llandovery-Wenlock (Silurian) palynology of the Pentland Hills inliers, Midland Valley of Scotland

The results of a palynological study on late Llandovery-Wenlock (mid-Silurian) successions in the North Esk, Bavelaw Castle and Loganlee inliers of the Pentland Hills, Midland Valley of Scotland, are documented. Palynological assemblages from the Reservoir Formation are dominated by acritarchs, but chitinozoa, cryptospores and scolecodonts are also present. Assemblages from the lower part of the Reservoir Formation are of low diversity and abundance, but marked increases in both abundance and diversity, particularly of the acritarchs, occur in the upper 200 m or so of the formation. The reasons for the marked increases are unclear, but could reflect changing environmental conditions during deposition of the upper Reservoir Formation, with the marine palynomorphs tracking changes in the location of certain physical and chemical properties of water-masses, for example nutrient availability, salinity or temperature. There is a general decline in the abundance and diversity of acritarchs and chitinozoans above the Reservoir Formation, although both groups, together with rare cryptospores, are present in samples from the Deerhope and Wether Law Linn formations. The Henshaw Formation yielded few marine microfossils, but more abundant and diverse spores and cyptospores than the underlying formations, consistent with an upward transition from marine to prograding terrestrial facies. The microfloras from the Reservoir, Deerhope and Wether Law Linn formations are consistent with the late Llandovery age indicated by graptolite evidence. A feature of assemblages from the Reservoir Formation, particularly the more productive samples from the upper part of the formation, is the common occurrence of sphaeromorph acritarchs, Moyeria cabottii and Tylotopalla species. The common occurrence of these forms gives the palynological assemblages a distinctive character. Similar sphaeromorph-Moyeria-Tylotopalla dominated acritarch microfloras occur at about the same level (spiralis Graptolite Biozone) in the Silurian succession of the Girvan Inlier, in the Drumyork Flags Formation. They might therefore be useful for correlating upper Llandovery rocks across the Midland Valley

Structure and post-translational modifications of the web silk protein spidroin-1 from Nephila spiders

Spidroin-1 is one of the major ampullate silk proteins produced by spiders for use in the construction of the frame and radii of orb webs, and as a dragline to escape from predators. Only partial sequences of spidroin-1 produced by Nephila clavipes have been reported up to now, and there is no information on post-translational modifications (PTMs). A gel-based mass spectrometry strategy with ETD and CID fragmentation methods were used to sequence and determine the presence/location of any PTMs on the spidroin-1. Sequence coverage of 98.06%, 95.05%, and 98.37% were obtained for N. clavipes, Nephila edulis and for Nephila madagascariensis, respectively. Phosphorylation was the major PTM observed with 8 phosphorylation sites considered reliable on spidroin-1 produced by N. clavipes, 4 in N. madagascariensis and 2 for N. edulis. Dityrosine and 3,4-dihydroxyphenylalanine (formed by oxidation of the spidroin-1) were observed, although the mechanism by which they are formed (i.e. exposure to UV radiation or to peroxidases in the major ampullate silk gland) is uncertain. Herein we present structural information on the spidroin-1 produced by three different Nephila species; these findings may be valuable for understanding the physicochemical properties of the silk proteins and moreover, future designs of recombinantly produced spider silk proteins. Biotechnological significance: The present investigation shows for the first time spidroin structure and post-translational modifications observed on the major ampullate silk spidroin-1. The many site specific phosphorylations (localized within the structural motifs) along with the probably photoinduction of hydroxylations may be relevant for scientists in material science, biology, biochemistry and environmental scientists. Up to now all the mechanical properties of the spidroin have been characterized without any consideration about the existence of PTMs in the sequence of spidroins. Thus, these findings for major ampullate silk spidroin-1 from Nephila spiders provide the basis for mechanical?elastic property studies of silk for biotechnological and biomedical potential applications. This article is part of a Special Issue entitled: Proteomics of non-model organisms

Biostratigraphy of late Llandovery (Telychian) and Wenlock turbiditic sequences in the SW Southern Uplands, Scotland

In the SW part of the Southern Uplands of Scotland the relatively thin Moffat Shale Group (late Ordovician–early Silurian) is succeeded by a thick development of Silurian greywackes, of variable turbiditic facies. This includes late Llandovery (Telychian) quartzose greywackes with interbedded thin graptolitic shales of the turriculatus and crispus biozones, in the upper part of the Gala Group, a sequencewhich is laterally equivalent to the basal part of the Hawick Group. The age of the finer-grained calcareous Hawick Group, which here includes 1. the Ross Formation, ranges from late Llandovery (turriculatus Biozone) to early Wenlock (riccartonensis Biozone). The Riccarton Group, which contains thick units of thinly-bedded siltstones and mudstones, is of Wenlock age (riccartonensis to lundgreni biozones). Within this sequence, all the biozones of the standard graptolite zonal scheme have been recognised in the area, with the exception of the crenulata Biozone of the late Llandovery (Telychian Stage) and the murchisoni and ellesae biozones of the Wenlock (Sheinwoodian Stage). Details of the graptolite biostratigraphy areclosely comparable with those of the markedly thinner sequences of northern England. Acritarchs occur throughout the sequence but are most numerous and best preserved in the Gala Group. Poorly preserved chitinozoa and spores are also present, the former occurring sporadically throughout the succession but the latter become common only in the Riccarton Group